The most noticeable feature of Biome Diversity (Birch Forest, Swamp, Mesa Islands) Seed is the spawning place, which is on an island with the C shape. However, remember to choose the creative mode when you play this seed.
After spawning, you should walk ahead and turn left until you see a big birch forest. Walk straightly, and you no longer see a swamp biome.
Turn right, and you will find some mesa islands. Discover the special mesa islands to get much gold.
There is an open cave entrance that is underneath the big mesa mountain. It offers an abundant source of gold, iron, and gold. Quickly mine it now.